Structural member with multi-layered gypsum board fire protection



NOV. 16, 1965 P. s. QUIGG ETAL STRUCTURAL MEMBER WITH MUTI-LAYEREDGYPSUM BOARD FIRE PROTECTION Filed Oct. l2, 1962 l Ew pla S. Qur-yg,Nels /Velgsmy United States Patent C) 3,217,456 STRUCTURAL MEMBER WITHMULTl-LAYERED GYPSUM BOARD FIRE PROTECTION Paul S. Quigg, Barrington,and Nels Nelsson, Des Plaines,

Ill., assignors to United States Gypsum Company,

Chicago, Ill., a corporation of Illinois Filed Oct. 12, 1962,Ser. No.230,059 1 Claim. (Cl. 52-423) This invention pertains to tire resistantbuilding constructions and more particularly to gypsum board coveringsfor retarding the effects of fire upon structural elements.

One important criterion in building constructions is the ability of thestructure to withstand the effects of lire. Acceptable structures mustbe capable of retaining their structural integrity for a substantialperiod of time even through subjected to an internal or externalconflagration. This quality of a structure and/ or its components towithstand re conditions is commonly known as its lire rating and ismeasured in increments of time signifying the period for which theconstruction will maintain prescribed parameters, such as temperature,strength, or non-combustion of the components, under specified testconditions. One accepted standard for lire endurance ratings of the typeof element to which this invention pertains is UnderwritersLaboratories, Inc. testStandard for Fire Tests of Building Constructionand Materials UL 263 (NFA 251, ATSM E 119). Fire ratings discussedhereinafter will be with reference to such a standard, except as mayotherwise be noted.

An extremely important aspect of providing a satisfactory fire enduringbuilding construction is the protection of the main frame members andparticularly the support columns. The present invention will bedisclosed and described herein with reference to this use and moreparticularly with reference to the fire protection of steel columns suchas are used in many commercial type buildings.

When utilizing steel structural members it is normally necessary toprotect them with coverings of suitable materials, such as gypsumpanels, plaster, Portland cement concrete, or the like, to meet buildingcode fire ratings which are usually prescribed by local authorities.Such codes normally require a minimum rating of two hours according to astandard fire endurance test such as that noted above. This however ismerely a minimum rating required for approval of the construction.Notwithstanding the fairly common acceptance of a two hour ratedconstruction by local authorities, an important reason for obtainingeven higher re ratings has arisen from the present and increasing demandby insurance underwriters that structural members be suflicientlyprotected to achieve a minimum fire rating of three hours as addedprotection against re losses.

Along with the requirements for high re ratings, there remains the everpresent necessity for economy of time and materials in buildingconstructions. Consequently it is highly desirable that high iireratings be obtained with constructions which may be easily and simplyformed without the provision of special equipment and/or materials orthe application of special skills.

The present invention provides an advantageous approach to theaforenoted problems by obtaining a high fire rating with componentswhich are commonly utilized in so-called drywall interior constructionsand are thus readily available. This, in turn facilitates erection andcompletion of a building as all interior constructions, including fireprotection members, may be fabricated of the drywall components.

3,217,456 Patented Nov. 16, 1965 we ICC It is an object of thisinvention to provide an improved fire enduring covering of gypsum boardpanels for structural members, utilizing a minimum number of layers ofpanels to achieve maximum lire endurance ratings.

It is another object of this invention to provide improved fire enduringcoverings for structuralfmembers which obtain high fire ratings andwhich may be conveniently and economically included in a buildingconstruction.

Further and additional objects and advantages will appear from thefollowing description, accompanying drawings and appended claims.

In carrying out this invention in one illustrative form, a structuralmember is encased in superimposed layers of gypsum board panels, thepanels of each layer forming joints Where the -edges of the panels meet,with an incombustile cover member secured over each of these joints.Adhesive material such as joint compound bonds each overlying layer ofpanels to the ysubjacent panels, -and wire binding members extend aroundeach layer of panels and the respective cover members, except theoutermost layer. Additional joint compound `is applied to -and V1inishesthe exterior surface of the outer layer of panels.

For a more complete understanding of this invention, reference shouldnow be had to the example illustrated in the accompanying drawingswherein:

FIG. l is a perspective View of a structural member with a re protectivecovering employing theteachings of this invention, the encasing coveringbeing partially broken away;

FIG. 2 is a horizontal cross-sectional View of the construction in FIG.l;

FIG. 3 is a partial cross-sectional View taken along lines 3 3 of FIG. 2and looking in the direction of the arrows;

FIG. 4 is an enlarged perspective view of a portion of one of the jointcover members utilized in the construction of FIG. 1, and

FIG. 5 is a partial cross-sectional view similar to FIG. 2 butillustrating an alternate surface treatment.

Referring now to the drawings, and more particularly to FIGS. l, 2 and3, a fire protective construction 18 is disclosed as applied to andenclosing a steel I-beam column 20 comprising a web 21 and anges 22.

The column-encasing lire protective construction 18 includes a firstlayer of gypsum board panels 24 arranged around and enclosing the member20 over its full exposed length. When the structural member 20 is of arectangular peripheral conguration as illustrated, the `panels24 lmay beof a width greater than the corresponding sides of the structural memberby an amount equal to the. panel thickness, whereby the panels fitsnugly against the member and form neat, closed, overlap joints at eachcorner. Cover members 26a of an incombustible material are then placedover each of the corners and cover the joints between the panels 24.

The angle members 26, illustrated in FIG. 4 l(26a, 'b and c in theremaining figures) each comprise a metal angle having a pair ofangularly disposed flanges 28 joined by a bulbous arcuate ridge or bead29 which projects outward of the planes defined by flanges 28. The bead29 facilitates placement of the flanges against the panel edgesregardless of such slight irregularities as may occur at the corners ofthe panels 24 and-may serve as aground for applying other materials suchas joint compound. Holes may be formed in the flanges as at 28a wherebylplastic joint compound placed over the lmembers 26 will pass throughthe holes, bond to the edgesof subjacent panels and key the resultingstructure together.

When two or more artisens cooperate in applying the components of thisconstruction to a structural member, the angle members 26a need not besecured to the edges of the panels since the artisans can cooperate andmaintain them in place until subsequent holding structure is applied.However, when a single artisan applies the components, it is convenientto tack or nail these angles to the panels for temporary holdingpurposes.

Flexible binding members 30 are next placed around the first layer ofpanels 24 and the cooperating angles 26a at spaced intervals over thelength of member 20. The binding members, which are of incombustiblematerials and preferably comprise steel wires, are drawn snug and tiedor otherwise suitably secured.

A layer of cement 32 is applied to the exposed surface of each of thepanels 24, prior to the application of the next layer of panels. Thecement 32 should be distributed over substantially the entire exposedsurface of the panels 24, and be of. a depth to extend outward tiushwith or beyond the outer surface of the binding members 30. This may beaccomplished by trowelling on a smooth continuous layer of cement, or byutilizing a notched trowel to form spaced ridges of the requisiteheight, or the cement may be otherwise distributed in a continuous ordiscontinuous layer, so long as the resulting cement layer contacts theadjacent panels over substantially the entire area of their opposedsurfaces after the overlying layer of panels 34 is pressed into place.

The second layer of panels comprising gypsum board panels 34 is thenapplied over the previously assembled structure, the panels 34 alsobeing of a width to form overlap joints at each corner. The panels ofthis second layer will normally be held in position by the cement 32previously applied to the exposed surface of the rst layer of thepanels. Angle cover members 2Gb are placed over the corners of panels 34to cover the joints therebetween and are secured in position by drivingsuitable fasteners 36a, such as metal screws, through the flanges of theangles 2Gb, through the underlying edges of panels 34 and through theflanges of the underlying angle members 26a. Flexible binding members36, similar to members 30, are placed around the panels 34 and cornermembers 26b, drawn snug and secured, and a layer of cement 38 isdistributed over the exposed surface of the panels 34 of this secondlayer in the same rnanner described above regarding cement layer 32.

Additional intermediate layers, such as the second layer of panels andrelated angle members, binding members and cement, may be applied in thesame manner as the second layer.

The surface or finish layer construction is formed of panels 40 whichare cut and applied to form overlapping edge joints as in the precedinglayers. Corner members 26C are then applied over the corners in the samemanner as the corner members 2Gb of the second layer, the corner members26C being secured in place by fasteners 3612 extending through theflanges thereof, through the edges of the underlying panels 40 andthrough the flanges of the underlying corner members 26h. The anges ofcorner members 26C are then covered with joint cement 42 flush with thebeads 29 of these members, and the cement feathered out over the panels40 to provide a smooth planar appearing surface. The iinal la'yer ofcement 42 provides a finished appearing surface to re- Ceive suitabledecorative materials where desired.

The alternative construction illustrated in FIG. is the same as thatillustrated and described with reference to FIGS. l-3 except that thefinal exposed layer of cement 44 covers the panels 40 to the depth ofthe beads 29 of the angle members 26C and provides the finishedappearing external surface.

The cement utilized to adhere the various panels together and to finishand/ or cover the external surface of the outer layer may preferably bea joint compound, such as a casein or polyvinyl acetate base with asuitable filler, sometimes referred to as joint cement in the drywallindustry. By way of example, suitable joint compounds are discussed inU.S. Letters Patent No. 3,003,979 to Ptasienski and Gill, and No.2,047,982 to Page.

By way of one specic illustration of a construction embodying thisinvention, a steel column was covered in accordance with the disclosurein FIG. 5 utilizing panels about 5/8" in thickness and comprising papercovered cores of set calcined gypsum meeting Underwriters Laboratories,Inc., classification Wallboard, Gypsum Guide No. 40 U 18.23, and soldunder the trademark Firecode by United States Gypsum Cornpany, Chicago,Illinois. The binding members were 18- gauge double strand steel wiresof circular cross section, distributed over the length of the column ata maximum spacing of about 2l apart, and with a maximum spacing of about6" from each end of the construction. The cover members were angularcorner members of 26 gauge (U.S. Standard) galvanized steel with eachange being about l in width. The fasteners extending between pairs ofoverlying joint covering members were threaded, self-tapping rotarydrywall metal fasteners of the type described in U.S. Letters Patent No.3,056,234 to Nelsson and Knohl, about 1" in length, and placed on l2centers along each cover flange. Joint compound sold under the trademarkPerf-A-Tape by United States Gypsum Company of Chicago, Illinois, wasutilized between successive panel layers and spread with a notchedspreader to leave lines or rows of compound which were semicircular incross section, with diameters of about 3/8, and on about ll/sl centers;this resulted in a compound bonding layer about 1746 thick after theoverlying panels were secured in position. The outer sur-face finishinglayer was also joint compound about le," thick.

When tested according to the aforenoted Underwriters Laboratories, Inc.,test, the construction described above provided a tire rating of about 3hours and 33 minutes.

The importance of the combination of features disclosed and claimedherein can perhaps best be illustrated by comparison of there ratingtest results on the foregoing example with the results of tests on otherstructures. For instance in three National Bureau of Standards tests onsteel columns protected by layers of 1/2" thick gypsum board panels andjoint compound between the panel layers, but without the metal cornerjoint covering members, the following results were obtained:

Test Construction Rated,

hours.

No. 315-5-22-52-4 Steel column protected with [our layers 2% layers. ofVZ panels, fit with edge overlap and cut in lengths to cover the columnheight. Each layer applied vertically with joint compound to bond innerlayer to column and successive layers to each other. Tied around thecolumn with double strands of 18 ga. tie Wire spaced 15" apart afterthird layer is in place. Outer corners finished with joint compound andpaper tape.

Steel column protected with three layers cut and applied as above exceptfirst two layers cemented and clinch-nailed together; then tied aroundcolumn with double strands of 18 ga. tie Wire spaced 15" apart. Thirdlayer then applied and outer corners finished with joint compound andpaper tape.

Steel coltunn protected with two layers 1 cut and applied as in fourlayer construction above, except inner layer tied around column withdouble strands of 18 ga. tie wire, spaced 15 apart. Corners of facelayer finished with joint compound and paper tape.

1% layers.

layers.

In other tests utilizing 5A thick gypsum board panels as designatedabove in the specific example of the present invention, together withmetal angle corner joint covering members, but without cement betweenthe panel layers, the following results were obtained under theaforenoted Underwriters Laboratories tests:

Test Construction Rated About 2 hrs., 33 min.

1-24-61-4 layers. Steel column protected with four layers of panels fitwith edge overlap and out in engths to cover the column heights. Eachlayer applied vertically; the Iii-st and second layers each tied with VZhigh tensile strength .015 thick metal straps spaced 2 apart. Corners ofthe second, third and fourth layers covered with metal angles, withscrews fastening the angles of the third layer to the angles of second,and the fourth to the third. Outer corners and layer nished with jointcornpound.

Steel column protected With three layers of panels, tied around the twoinner layers similarly to the four layer construction above except with1'6" spacing from the oor slabs and 26 spacing between ties. Corners atthe rst, second and third layers covered with metal angles, with screwsfastening the angles of the second layer to angles of the first layer,and the third to the second. Outer corners finished with joint compound.

Steel column protected with three layers of panels, tied around thesecond layer with metal straps as in the four layer construction aboveexcept with 16 Spacing from the floor slabs and 26 spacing between ties.Corners at the second and third layers covered with metal angles, withscrews fastening the angles oi the third layer to the angles of thesecond. Outer corners and layers finished with joint compound.

About 2 hrs., 33 min.

11-14-60-3 layers 9-16-60-3 layers About 2 hrs., 25

min.

The re rating of 3 hours and 33 minutes obtained with the constructionaccording to the previously described specic illustrative embodiment ofthe present invention was thus one hour longer than the ratings of otherlaminated panel constructions, even though the other constructionsincluded as many as three, or even four layers of panels.

It will thus be seen that a novel construction has been disclosed andtaughtwhich utilizes inexpensive and readily available components toprovide an advantageous high fire rating covering for structuralelements. Further, the high iire rating constructions of this inventionmay be fabricated with the same components normally utilized in drywallconstructions, thereby permitting the use of the same elementsthroughout the interior construction of a building and thus furtherenhancing the simplicity and economy of building construction.

While a particular embodiment of this invention is shown above andillustrated in the specific example, it will be understood, of course,that the invention is not to be limited thereto, since manymodifications may be made by those skilled in the art in light of thedisclosure and teachings herein. It is contemplated therefore by theappended claim to cover any such modifications as fall within the truespirit and scope of this invention.

We claim:

A fire enduring construction enclosing a structural member, comprisingrst, second and third successive superimposed layers of panelssurrounding such structural member over its full exposed length, each ofsaid panels Comprising a paper covered core of set calcined gypsum, saidpanels of each layer being disposed in edge-overlapping relation formingcorners Where the edges of adjacent panels meet, said corners ofsuccessive layers being juxtaposed, a metal angle corner member securedover each corner of each layer, fastening members securing said covermembers over said second and third layers to said cover members oversaid first and second layers respectively, a plurality of incombustiblebinding members eX- tending around said panels and cover members of eachinner layer and distributed over the length of said construction, andlayers of joint compound bonding said panels of said second and thirdlayers to the panels of said rst and second layers respectively oversubstantially their entire area.

References Cited by the Examiner UNITED STATES PATENTS 646,503 4/ 1900OShea 52-725 X 2,047,982 7/1936 Page 52-417 2,063,010 12/1936 Balduf52-241 X 2,267,929 12/1941 Lefebure et al. 52-725 2,797,573 7/1957Hummer 52-254 X 2,851,741 9/1958 Stemples 52-255 2,969,616 1/ 1961Gustafson 52-278 X 3,05 6,234 10/ 1962 Nelsson et al 52-363 OTHERREFERENCES Architectural Forum (a publication), February 1952, page 22.

Building Materials List, published by Underwriters Laboratories Inc.,January 1961, page 66.

FRANK L. ABBOTT, Primary Examiner.

JACOB L. NACKENQFF, HENRY C. SUTHERLAND,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No.3,217,456 November 16, 1965 Paul S. Quigg et a1.1

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

In the sheet of drawings, line 2 of the heading, for "MUTI-LAYERED" readMULTI-LAYERED column 1, line 18, for "through" read though line 29, for"ATSM" read ASTM column 2, 1ines 15 and 16, for "incombustile" readincombustble line 69, for "artsens" read artisans column 5, in thetable, second column, 1ine 3 thereof, for "engths" read lengths Signedand sealed this 13th day of September 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

